"It was painful. It's not easy. You put a lot of time and effort into it, so it's emotional," Jackman said. "I think any parent can relate -- trying to have children is wonderful and when you feel as though that's not going to happen, there's a certain anxiety that goes with it."

The couple tried in vitro fertilization to boost their chances of having biological children, but after several failed attempts, "we went ahead with adoption."

Adopting son Oscar, 11, and daughter Ava, 6, turned out to be the best decision of Jackman's life. "From the moment we started the adoption process, all the anxiety went away. I don't think of them as adopted -- they're our children."

"We feel things happened the way they are meant to," he added. "Obviously, biologically wasn't the way we were meant to have children."